Water Pump Especially for Ponds, Aquariums, Fountains or the Like

ABSTRACT

A water pump has a housing with a pump housing part, provided with an intake opening and an exit opening, and a motor housing part. An impeller with a shaft is rotatably arranged in the pump housing part. An electric pump motor is arranged in the motor housing part, wherein the pump motor comprises a stator having several coils arranged on several stator poles and a rotor rotating in the stator. The pump motor is an electronically communicated motor. The stator is comprised of a pack of unitary laminations, respectively. The pump motor has control electronics arranged in the motor housing part. The stator with its coils and the control electronics are water-tightly encapsulated.

BACKGROUND OF THE INVENTION

The invention concerns a water pump especially for ponds, aquariums, fountains or the like, having a housing comprising a pump housing part, provided with an intake opening and an exit opening. In the housing an impeller with a shaft is rotatably arranged. A motor housing part is provided in which an electric motor with a stator having several coils arranged on several stator poles and a rotor rotating therein is received. The pump is to be configured for a power range between approximately 100 and 900 Watt. Such already relatively large pumps for use in ponds have in practice asynchronous motors that require a high material expenditure and are therefore relatively expensive. Also, their efficiency is often not satisfactory.

Small pumps are partially already driven by synchronous motors but must be connected to complex control devices. In this case, the sealing of the electrical parts and connections is sometimes difficult.

SUMMARY OF THE INVENTION

The invention concerns therefore the problem of providing a water pump whose efficiency in comparison to conventional pumps of the same power class is increased and that can be manufactured less expensively and can be operated comfortably.

This problem is solved in accordance with the invention by a water pump wherein the motor is an electronically communicated motor; the stator is comprised of a pack of unitary laminations, respectively; control electronics for the motor are arranged in the motor housing part; and the stator with the coils and the control electronics is water-tightly encapsulated.

By using an electronically commutated motor, the efficiency of the pump can be significantly increased within a power range of approximately 100 to 900 Watt wherein the manufacture of the pump motor with a stator comprised of a pack of unitary sheet metal laminations can be effected in a material-saving and cost-reducing way. By incorporating control electronics for the motor control directly into the pump and arranging them within the motor housing part and encapsulating them together with the stator and the coils in a water-tight way, the risk of repairs of the pump can be minimized because all essential electric and electronic components are combined and perfectly protected from water by means of encapsulation.

With regard to efficiency and cost, the pump can be optimized when a two-pole permanent magnet is used as a rotor and a stator with six stator poles and therefore six coils received thereon is used. The two-pole permanent magnet rotor can be essentially comprised of a unitary two-pole magnet ring that is diametrically magnetized. It can be produced in a simple and thus inexpensive way.

The stator is comprised according to the invention of a plurality of stacked stator sheet metal laminations that are stamped as unitary parts. This reduces the assembly costs in comparison to multi-part stators in which the stator poles are individually inserted.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and details result from the dependent claims and an embodiment illustrated in the drawings which will be described in the following. It is shown in:

FIG. 1 a perspective external view of a pump according to the invention;

FIG. 2 a longitudinal section of the pump of FIG. 1;

FIG. 3 a cross-section of the stator of the pump motor in the plane III of FIG. 2 when mounting the coils;

FIG. 4 the object of FIG. 3 with completely mounted coils; and

FIG. 5 a perspective illustration of the object of FIG. 4 without windings on the coils.

DESCRIPTION OF PREFERRED EMBODIMENTS

The pump illustrated in FIG. 1 has a housing 1 that is essentially comprised of a pump housing part 2 and a motor housing part 3. The pump housing part 2 has an intake opening 4 and an exit opening 5 for water to be pumped. The two housing parts 2, 3 are connected in a simple way with one another, for example, as illustrated, by a bayonet closure 6 with additional screw connection 7.

The interior of the pump is illustrated in section in FIG. 2. Between the intake opening 4 and the exit opening 5, an impeller 8 is arranged in the pump housing part 2 on the shaft 9; the shaft is preferably made of ceramic material. The impeller and the shaft 9 are driven in rotation by means of an electronically commutated motor (EC motor) that is arranged in the motor housing 3. The shaft 9 extends from the pump housing part 2 into the motor housing part 3 wherein the motor is shielded from the impeller 8 mechanically by a bearing bracket 10.

The motor is comprised essentially of a stationary stator lamination pack 12 on which coils 13 that are also stationary are provided as well as a rotor 14 which in the illustrated embodiment is advantageously formed as a two-pole permanent magnet. Between rotor 14 and shaft 9 there is a solid, closed iron ring 15 that is fixedly connected to both rotor and shaft and increases the magnetic flux of the motor significantly.

On the back of the motor a circuit board 16 is arranged that comprises the entire control electronics. Finally, the motor has a ground 17 at the stator 12 and a ground plate 18 at the back of the motor housing part 3.

For sealing the housing part 2 through which the water flows relative to the housing part 3 that receives the electric components, the rotor 14 with all movable parts and the stator 12 with all parts through which current flows are separated from one another by a can 19 surrounding the rotor 14. Toward the pump housing part 2 the can 19 widens into a large color-shaped flange 19′ for completely separating the pump housing part 2 and the motor housing part 3. The interior of the entire motor housing part 3 is encapsulated so that all free spaces are filled, for example, with a synthetic resin. The encapsulating compound 20 thus embeds also the entire control electronics 16 so that the latter are not only protected from moisture but also protected mechanically against vibrations. At the same time, the encapsulating compound 20 also supports the can 19 so that it can be manufactured inexpensively of plastic material that is not reinforced externally.

The control electronics 16 may comprise a signal evaluation unit, not illustrated in detail, by which the received signals are used for speed regulation of the pump motor. The control signals can be modulated directly by the mains voltage that is supplied to the motor. In this way, it is not necessary to provide a complex phase cutting control for speed regulation of the pump as it has been used up to now for conventional motors. The operation for speed regulation can be realized in particular by means of an intermediate switch that can be remote-controlled and is arranged between the mains supply and the current supply cable for the pump. This intermediate switch comprises a receiving module that receives the signals emitted by the remote control for changing the motor speed. In the intermediate switch element these signals are modulated onto the mains current and in this way transmitted to the control electronics of the pump. The intermediate switch thus takes on only the task of signal transfer so that no power electronics are required.

In the illustrated embodiment the stator 12 and the correlated coils 13 are preferably configured such that the coils 13 when being mounted can be slipped onto stator poles 22 of the stator 12 from the interior. This and the configuration of the stator 12 with the coils 13 is illustrated in more detail in FIGS. 3 through 5. By being able to simply slip on the coil bodies 13, there is no need for using expensive threading machines for winding the coils as is needed in regard to other unitary laminations with pole shoes formed on the inner side. The stator poles 22 of the stator 12 of the pump according to the invention are therefore to be configured at their inner side essentially without widened portions so that slipping on the coils is possible.

The geometric conditions that enable that the coils 13 can be slipped onto the stator poles 22 are illustrated essentially in FIG. 3. For this purpose, the length a of the coils 13 must be smaller than the minimal spacing A1 of two opposed inner pole sides as well as smaller than the length A2 of the individual stator poles 22. Moreover, the width b of the coils 13 must be less than the minimal spacing B1 of an inner pole edge 42 to the inner pole edge 42 of the second to next stator pole 22, respectively; i.e., between the two stator poles in question precisely one additional stator pole 22 is located. The width b of the coils 13 must also be smaller than the minimal spacing B2 of two outer edges of the coils in the mounted state between which again a further coil 13 or a further stator pole 22 is located. Finally, the width c of the stator poles 22 is to be selected smaller than the inner width C of the coils 13.

The pump according to the invention is optimized in that, on the one hand, its dimensions are to be kept as small as possible and, on the other hand, its efficiency should be as high as possible; this should be achieved while the assembly should be improved. For increasing the efficiency at predetermined maximum dimensions, the geometric conditions must be selected such that the coils 13 on the one hand can still be slipped on and, on the other hand, as many windings as possible can be arranged on the coils 13. For this purpose, an arc length BL of the stator poles 22 must be defined. If in the interior of the stator 12 in which the rotor 14 rotates an imaginary circle of maximum size were positioned that contacts the inner sides 32 of the stator poles precisely, the sum of the arc length BL of all poles 22 could be precisely half of the circumference of the defined circle. For the benefit of the copper quantity to be arranged in the coil windings and for preventing flux scattering, the arc length BL of each stator pole 22 is however reduced preferably by approximately 11 percent to 12 percent relative to the above defined initial length.

Advantageously, an angle a can be defined between two straight lines 50 that extend from the stator center and touch the inner pole edges 42 of the stator poles; the angle is between 0.88 times 360 degrees divided by the number n of the stator poles 22 and approximately 0.89 times 360 degrees divided by the number n of the stator poles 22. For conditions optimized in this way, the coils 13 are inserted into the opening ds illustrated in FIG. 3 and are then slipped onto the stator poles 22 until they meet the stop.

The stator 12 of the illustrated embodiment has precisely six stator poles 22. Depending on the requirements, it is also possible to provide the motor with a stator 12 having three, nine, twelve, fifteen stator poles. However, for more than six poles 22 the spacings for the windings of the coils 13 are very narrow so that the mounting expenditure and cost expenditure will be increased. However, a motor that has only three poles has a reduced efficiency.

The pump according to the invention is characterized by high mounting comfort, minimal manufacturing costs, a high efficiency, and an optimized operating comfort. It is not prone to failure and therefore can be used without requiring much maintenance. Because of its high efficiency and the reduced material expenditure, the energy demand of such a pump in regard to manufacture as well as operation is minimized.

The specification incorporates by reference the entire disclosure of German priority application 10 2006 027 001.0 having a filing date of Jun. 8, 2006.

While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles. 

What is claimed is:
 1. A water pump comprising: a housing comprising a pump housing part, provided with an intake opening and an exit opening, and a motor housing part; an impeller with a shaft rotatably arranged in the pump housing part; an electric pump motor arranged in the motor housing part, wherein the pump motor comprises a stator having several coils arranged on several stator poles and a rotor rotating in the stator; wherein the pump motor is an electronically communicated motor; wherein the stator is comprised of a pack of unitary laminations, respectively; wherein the pump motor has control electronics arranged in the motor housing part; and wherein the stator and the coils and the control electronics are water-tightly encapsulated.
 2. The water pump according to claim 1, wherein the rotor is embodied as a two-pole permanent magnet.
 3. The water pump according to claim 1, wherein the coils are pushed onto the stator poles from the interior of the stator.
 4. The water pump according to claim 1, wherein the pump motor further comprises a can that separates the rotor and the stator from one another.
 5. The water pump according to claim 4, wherein the can is comprised of plastic material that is not externally reinforced.
 6. The water pump according to claim 1, wherein the pump motor further comprises a solid, at least substantially closed iron ring that is arranged between the rotor and the shaft.
 7. The water pump according to claim 1, wherein the control electronics have a signal evaluation unit that evaluates signals modulated onto mains current supplied to the water pump and employs the signals for speed regulation of the pump motor.
 8. The water pump according to claim 1, wherein for the stator and the coils the following geometric conditions apply: a < A1 a < A2 b < B1 b < B2 c < C,

wherein: a=length of the coils; A1=minimal spacing between two opposed inner pole sides of the stator poles; A2=length of the stator poles; b=width of the coils; B1=minimal spacing of two inner pole edges of the stator poles, between which inner pole edges precisely one other stator pole is located; B2=minimal spacing of two outer coil edges of the coils in the mounted states, between which precisely one other coil is located; c=width of the stator poles; C=inner width of the coils.
 9. The water pump according to claim 8, wherein an inner arc length of the stator poles is reduced by approximately 11 percent to 12 percent relative to a circumference of a circle contacting the inner pole sides of the stator poles and divided by twice the number of the stator poles.
 10. The water pump according to claim 8, wherein for the stator approximately the following geometric condition applies: 0.88×360 degrees/n<=α<=0.89×360 degrees/n wherein: α=angle between two straight lines extending from the stator center and touching the inner pole edges of the stator poles; n=number of stator poles. 